Altered excitation-inhibition balance in the brain of patients with diabetic neuropathy

Rationale and objectives: To assess differences in excitatory (glutamate/glutamine or Glx) and inhibitory (γ-Aminobutyric acid or GABA) neurotransmitter levels using MR spectroscopy in pain processing regions of the brain in patients diabetic neuropathy (DN) and positive sensory symptoms and age-matched healthy control (HC) subjects.

Materials and methods: Seven diabetic patients (5 males, 2 females, mean age = 57.0 ± 8.5 years) with confirmed DN and positive sensory symptoms and 7 age and sex matched HC subjects (mean age = 57.7 ± 3.2 years) underwent 3 Tesla MR spectroscopy. Glx and GABA levels were quantified in the right anterior and posterior insula, anterior cingulate cortex and right thalamus.

Results: Mean Glx levels were significantly higher and mean GABA levels were significantly lower within the posterior insula in the DN patients compared to HC (P = 0.005 and 0.012 respectively).

Conclusions: This pilot data demonstrates an excitatory/inhibitory neurotransmitter imbalance in the brain of in patients with DN and positive sensory symptoms compared to pain free HC subjects.